Approximately a third (31%) of adult Americans are prehypertensive (SBP 120-139 and/or DBP 80-89). Health care providers struggle to provide effective support for blood-pressure-lowering behavior changes, while patients continue to progress to full hypertension and the use of antihypertensive medications. Insurers and providers with access to electronic medical records and other medical data are in a unique position to identify prehypertensive adults and target them with a blood pressure self-management program. Preventing or delaying hypertension should reduce mid-term costs of antihypertensive medications and, more importantly, long-term costs of care for heart disease and stroke. This project will develop and evaluate a coach-guided, interactive blood pressure self-management program for adults with prehypertension. The program will target blood pressure self-monitoring and the five proven lifestyle modifications recommended by JNC-7: weight reduction, the Dietary Approaches to Stop Hypertension (DASH) diet, sodium reduction, physical activity, and alcohol consumption. The multi-modal program uses a combination of brief motivational health coaching, periodic engagement emails, and a robust interactive website to motivate people to take charge of their blood pressure management before they require medication. All program components were designed to conform to the underlying principles of motivational interviewing. Key program components include the use of email and Web-based social networking, personal stories, and brief motivational coaching sessions to engage participants and encourage intrinsically motivated behavior changes. Self-assessment and tracking tools are combined with educational content to help participants align their daily lifestyle choices with their personal goals. The Phase I prototype program promoted moderate physical activity and eating fruits and vegetables as part of the DASH diet. Results from the within-group (n = 39) evaluation showed moderate-to-large effect sizes for pre-to-post change in motivation, preparation behavior, self-efficacy, attitudes, and knowledge, and a small significant increase in physical activity. Participants gave the online program high ratings on satisfaction and usability, and reported improvements in confidence, readiness, clarity, change strategies, and interest in visiting the Website as a result of the coaching session. The fully developed Phase II product will be evaluated in a large randomized trial (N = 450) with a 3-month intensive period, a 3-month maintenance period, and a 3-month follow-up period. The Phase II trial is expected to show improvements in JNC-recommended BP-lowering health behaviors. These changes in the outcome measures are expected to be mediated by changes in knowledge, attitudes, self-efficacy, behavioral intention, motivation, and patient activation. The Phase II product will be marketed to large, integrated health benefits providers with both insurance and wellness products, like our Phase II evaluation partner Aetna, and to integrated health service delivery systems, like our Phase I and II evaluation partner, Providence Health.